Shadow of the Colossus and ICO for sure take the top 2 spots for me. I also really liked Okami. The Ratchet & Clank Series was probably my favorite series on PS2 and I would put Up Your Arsenal in my top 5 for the system. I can't forget any of the Grand Theft Auto games either or the Metal Gear Solid games or Dragon Quest VIII or the Persona games. The PS2 had a lot of excellent games.